To the Editor:
Kopp et al. (1) should provide more details which could help to prevent or more effectively treat cardiac arrest after neuraxial anesthesia.
Preventing these arrests may require smaller doses of the local anesthetic. Many patients received excessive doses of local anesthetic before their arrests (40 mg of spinal tetracaine, 840 mg of chloroprocaine for caudal anesthesia, and 610 mg epidural lidocaine). Because smaller doses are recommended for elderly patients and for lower body procedures, there were a number of other overdoses in this series, including overdoses from a mixture of procaine and tetracaine for spinal anesthesia. A similar combination (Neocaine) was available in the 1930s, and larger overdoses were utilized in half of the deaths in this early series (2).
We also need to learn more from the resuscitations. Why did 50% of the patients that received epinephrine die? Was epinephrine given too late, or are these failures related to epinephrine itself (3)? Successful resuscitation may require a combination of intravascular fluids, vasopressor, and vagolytics. Were patients hypovolemic at the time of arrest? Was atropine associated with a more frequent rate of successful resuscitations than epinephrine?
Could more of the arrests be related to the neuraxial anesthetic? For example, when an elderly patient had a cardiac arrest after receiving 40 mg of spinal tetracaine was this at least partially related to anesthetic overdose? Much of this information could be provided by including in the response letter a summary like Table 5 from Biboulet et al. (4). Providing this information could highlight the need for more limited dosing of the local anesthetic, emphasize the importance of adequate fluid replacement, or help confirm or refute the value of atropine in this setting. We must learn all that we can from a series of this size and improve on current practice if we want to reduce the current 25% to 30% mortality rate from cardiac arrest after neuraxial anesthesia.
John Pollard, MD
Department of Anesthesiology
VA Palo Alto Health Care System
Stanford University School of Medicine
Palo Alto, CA
1. Kopp SL, Horlocker TT, Warner ME, et al. Cardiac arrest during neuraxial anesthesia: frequency and predisposing factors associated with survival. Anesth Analg 2005;100:855–65.
2. Thompson KW. Fatalities from spinal anesthesia. Anesth Analg 1934;13:75–9.
3. Liguori GA, Sharrock NE. Asystole and severe bradycardia during epidural anesthesia in orthopedic patients. Anesthesiology 1997;86:250–7.
4. Biboulet P, Aubus P, Dubourdieu J, et al. Fatal and non fatal cardiac arrests related to anesthesia. Can J Anaesth 2001:48:326–32.